2005 Vol. 27 No. 4
Abstract：
A new combined test apparatus is developed on torsion vibration principle, which can be used to measure shear-wave velocity and to determine cyclic liquefaction resistance of soil specimen simultaneously. The relation between the shear wave velocity and the cyclic liquefaction resistance is analyzed for a lot of undisturbed and remolded specimens of same kind of sand with same consolidation pressure, which are taken from more than 20 sites within the depth of 20 m under ground surface. The results show that the relation is good if the strain criterion for evaluating liquefaction is not larger than 6%.
A new combined test apparatus is developed on torsion vibration principle, which can be used to measure shear-wave velocity and to determine cyclic liquefaction resistance of soil specimen simultaneously. The relation between the shear wave velocity and the cyclic liquefaction resistance is analyzed for a lot of undisturbed and remolded specimens of same kind of sand with same consolidation pressure, which are taken from more than 20 sites within the depth of 20 m under ground surface. The results show that the relation is good if the strain criterion for evaluating liquefaction is not larger than 6%.
Abstract：
In the paper, thermo-stress in multilayered elastic half space is presented. Firstly, the stiffness matrix for a layer is derived based on the fundamental elasticity equations and some mathematic methods such as Hankel integral transformation. Then the global stiffness matrix is established for multilayered elastic half space using the finite element concepts in which layers are completely contacted. Therefore, explicit solution for axisymmetrical problems in multilayered elastic half space is obtained from the solution of the algebraic equation formed by global stiffness matrix and the inverse Hankel integral transformation. Because positive exponential function is not included in the element of matrix, the calculation is not overflowed. Therefore, the shortages of transfer matrix method are overcome. This method is clear in concept, and the corresponding formulas given in the paper are not only simple but also convenient for application. More important is that this method can be used to solve other problems of multilayered elastic half space such as thermo field and dynamics. An example of road surface deflection is presented to prove the calculated results.
In the paper, thermo-stress in multilayered elastic half space is presented. Firstly, the stiffness matrix for a layer is derived based on the fundamental elasticity equations and some mathematic methods such as Hankel integral transformation. Then the global stiffness matrix is established for multilayered elastic half space using the finite element concepts in which layers are completely contacted. Therefore, explicit solution for axisymmetrical problems in multilayered elastic half space is obtained from the solution of the algebraic equation formed by global stiffness matrix and the inverse Hankel integral transformation. Because positive exponential function is not included in the element of matrix, the calculation is not overflowed. Therefore, the shortages of transfer matrix method are overcome. This method is clear in concept, and the corresponding formulas given in the paper are not only simple but also convenient for application. More important is that this method can be used to solve other problems of multilayered elastic half space such as thermo field and dynamics. An example of road surface deflection is presented to prove the calculated results.
Abstract：
In this paper, a simple integral equation for scattering of Rayleigh wave has been deduced based on the fundamental solution of Lamb problem and elastic wave scattering theory. This method can deal with scattering of Rayleigh wave from irregular multi-obstacles by iteration. The convergence rapidity of the method has been proved very high by some practical examples, and usually the accurate solution can be obtained only through three to four times of iteration.
In this paper, a simple integral equation for scattering of Rayleigh wave has been deduced based on the fundamental solution of Lamb problem and elastic wave scattering theory. This method can deal with scattering of Rayleigh wave from irregular multi-obstacles by iteration. The convergence rapidity of the method has been proved very high by some practical examples, and usually the accurate solution can be obtained only through three to four times of iteration.
Abstract：
In this paper we present the exact analytical solutions for displacements and stresses of an isotropic non-homogeneous elastic subgrade on rock subject to an axisymmetric surface load. It is assumed that the soil of the subgrade is incompressible and that the shear modulus varies linearly with depth. Selected numerical results for vertical displacements are presented to describe the influence of the degree of non-homogeneity、depth of rock of the non-homogeneous subgrade. Hankel integral transforms are used in the analysis.
In this paper we present the exact analytical solutions for displacements and stresses of an isotropic non-homogeneous elastic subgrade on rock subject to an axisymmetric surface load. It is assumed that the soil of the subgrade is incompressible and that the shear modulus varies linearly with depth. Selected numerical results for vertical displacements are presented to describe the influence of the degree of non-homogeneity、depth of rock of the non-homogeneous subgrade. Hankel integral transforms are used in the analysis.
Abstract：
In this paper, the method and basic pattern of compound soil nail support are studied. Through engineering practice, the unsupported, simple soil nail support and compound soil nail support process are simulated and analyzed with finite element method. The obvious effects of application and deformation control of the compound soil nail support in the engineering practice have been verified .
In this paper, the method and basic pattern of compound soil nail support are studied. Through engineering practice, the unsupported, simple soil nail support and compound soil nail support process are simulated and analyzed with finite element method. The obvious effects of application and deformation control of the compound soil nail support in the engineering practice have been verified .
2005, 27(4): 393-397.
Abstract：
In this article, the author analyses the effect of media of the one-phase soil, unsaturated soil, saturated soil and soil layers structure with different modulus on seismic wave propagation, using dynanoic differential equations of two-phase media, and explicit finite element lumped-mass method with artificial transmitting boundary. It is shown that the character of media play an important role in P-wave propagation while the structure of soil layers has obvious effect on SV wave propagation. In the end, the author also illustrates that if the soil is laterally to unhomogeneous, the 1-D analysis would conduce to considerable error.
In this article, the author analyses the effect of media of the one-phase soil, unsaturated soil, saturated soil and soil layers structure with different modulus on seismic wave propagation, using dynanoic differential equations of two-phase media, and explicit finite element lumped-mass method with artificial transmitting boundary. It is shown that the character of media play an important role in P-wave propagation while the structure of soil layers has obvious effect on SV wave propagation. In the end, the author also illustrates that if the soil is laterally to unhomogeneous, the 1-D analysis would conduce to considerable error.
2005, 27(4): 398-402.
Abstract：
The durability, that is the service life of geosynthetics, is considered to be the primary problem when it will be chosen to use. The decay of mechanical performance is one of reliable indexes to evaluate the aging of geosynthetics. According to a series of tests and collected relevant test data, the theorefical model of mechanical durability of geosynthetics has been presented. The results obtained from the model show that if the initial tensile strength of geosynthetics is more than 500 N/5 cm with 40 cm thick covering soil, the service life of geosynthetics can be up to 50 years at least, and most can be over 100 years. It is concluded that the durability of geosynthetics is closely related to the natural environment temperature.
The durability, that is the service life of geosynthetics, is considered to be the primary problem when it will be chosen to use. The decay of mechanical performance is one of reliable indexes to evaluate the aging of geosynthetics. According to a series of tests and collected relevant test data, the theorefical model of mechanical durability of geosynthetics has been presented. The results obtained from the model show that if the initial tensile strength of geosynthetics is more than 500 N/5 cm with 40 cm thick covering soil, the service life of geosynthetics can be up to 50 years at least, and most can be over 100 years. It is concluded that the durability of geosynthetics is closely related to the natural environment temperature.
Abstract：
The static and dynamic universal triaxial and torsional shear apparatus of soil recently equipped in Dalian University of Technology is used to perform five types of tests for loose sands subjected to triaxial and torsional coupling cyclic shear and simple torsional shear. The effect of variation of principle stress orientation under cyclic loading on undrained cyclic shear behavior of Fujian Standard loose sand under isotropic consolidation condition is investigated. It has been shown through comparative tests that the change of orientation of principal stress during cyclic loading has a considerable influence on undrained dynamic strength of saturated loose sands. The dynamic strength under the cyclic rotation of principal stress axes is lowest among those obtained with five given types of stress paths of cyclic loading. The relationship between excess pore water pressure induced during vibration normalized with the initial effective confining pressure and the ratio of number of cycles with the cyclic number required at failure is independent of the variation mode of direction of principal stress during cyclic loading. Furthermore, both the change of the normalized excess pore water pressure with generalized shear strain and the change of the generalized shear strain with ratio of number of cycles are irrelevant to the change of orientation of principal stresses.
The static and dynamic universal triaxial and torsional shear apparatus of soil recently equipped in Dalian University of Technology is used to perform five types of tests for loose sands subjected to triaxial and torsional coupling cyclic shear and simple torsional shear. The effect of variation of principle stress orientation under cyclic loading on undrained cyclic shear behavior of Fujian Standard loose sand under isotropic consolidation condition is investigated. It has been shown through comparative tests that the change of orientation of principal stress during cyclic loading has a considerable influence on undrained dynamic strength of saturated loose sands. The dynamic strength under the cyclic rotation of principal stress axes is lowest among those obtained with five given types of stress paths of cyclic loading. The relationship between excess pore water pressure induced during vibration normalized with the initial effective confining pressure and the ratio of number of cycles with the cyclic number required at failure is independent of the variation mode of direction of principal stress during cyclic loading. Furthermore, both the change of the normalized excess pore water pressure with generalized shear strain and the change of the generalized shear strain with ratio of number of cycles are irrelevant to the change of orientation of principal stresses.
2005, 27(4): 410-413.
Abstract：
Lots of research work including the site investigation, sampling and testing of the cofferdam and its cut-off walls had been done during the period for the removal of stage II cofferdam of TGP. Some key factors are analyzed and discussed based on these results.
Lots of research work including the site investigation, sampling and testing of the cofferdam and its cut-off walls had been done during the period for the removal of stage II cofferdam of TGP. Some key factors are analyzed and discussed based on these results.
Abstract：
The first weight is the key of controlling mine pressure in fully-mechanized sublevel caving face. The course of top coal falling from beginning to end is a dynamic process. To set up the judgment rules of roof stability with the recovery ratio of top coal is an important theoretical problem. This paper establishes the mechanical model of the stability of the whole deformation of roof structure and the stability of partial contact of the main roof. Based on the structure stability theory and the strength theory, two kinds of limited convergence maintaining the stability of the whole deformation of roof structure and the stability of part contact of the main roof are obtained. According to the comparison of the two limited subsidence and the subsidence of roof caused by the movement situation of roof in the course of rotation, the unifying mechanical conditions between the stability of the whole transmutation of roof structure and the stability of part contact of the main roof are analyzed and the judgment rules of roof stability with the recovery ratio of top coal are established. Based on an example of fully-mechanized sublevel caving face, the judgment curve and method with the recovery ratio of top coal are put forward, the theoretical bases of designing the safe recovery ratio of top coal are provided for different roof, and the safe roof controlling is achieved at coal mine.
The first weight is the key of controlling mine pressure in fully-mechanized sublevel caving face. The course of top coal falling from beginning to end is a dynamic process. To set up the judgment rules of roof stability with the recovery ratio of top coal is an important theoretical problem. This paper establishes the mechanical model of the stability of the whole deformation of roof structure and the stability of partial contact of the main roof. Based on the structure stability theory and the strength theory, two kinds of limited convergence maintaining the stability of the whole deformation of roof structure and the stability of part contact of the main roof are obtained. According to the comparison of the two limited subsidence and the subsidence of roof caused by the movement situation of roof in the course of rotation, the unifying mechanical conditions between the stability of the whole transmutation of roof structure and the stability of part contact of the main roof are analyzed and the judgment rules of roof stability with the recovery ratio of top coal are established. Based on an example of fully-mechanized sublevel caving face, the judgment curve and method with the recovery ratio of top coal are put forward, the theoretical bases of designing the safe recovery ratio of top coal are provided for different roof, and the safe roof controlling is achieved at coal mine.
Abstract：
The resistance to deformation of artificially frozen soils in deep alluvium is investigated by relation between the secant Young’s modulus and the axial strain for different type of soil, loading or unloading, frozen temperature and initial confining pressure. It is observed that the stress-strain behavior of frozen soils in deep alluvium is highly nonlinear and the secant Young’s modulus might decrease with increasing strain, the limit of the elastic stage appeared similar for all conditions and was approximately 0.05% axial strain. On the other hand, the secant Young’s modulus of studied frozen soils and its degradation was closely related to the type of soils, loading or unloading, frozen temperature and initial confining pressure. Results indicate that the factors which can increase the secant Young’s modulus before yield of frozen soils would accelerates the rate of degradation of the secant Young’s modulus after yield of frozen soils.
The resistance to deformation of artificially frozen soils in deep alluvium is investigated by relation between the secant Young’s modulus and the axial strain for different type of soil, loading or unloading, frozen temperature and initial confining pressure. It is observed that the stress-strain behavior of frozen soils in deep alluvium is highly nonlinear and the secant Young’s modulus might decrease with increasing strain, the limit of the elastic stage appeared similar for all conditions and was approximately 0.05% axial strain. On the other hand, the secant Young’s modulus of studied frozen soils and its degradation was closely related to the type of soils, loading or unloading, frozen temperature and initial confining pressure. Results indicate that the factors which can increase the secant Young’s modulus before yield of frozen soils would accelerates the rate of degradation of the secant Young’s modulus after yield of frozen soils.
Abstract：
This article summarize the type and dynamic feature of karst water burst in Yuanliangshan tunnel, by means of analysis of water burst and filling materials of yuanliangshan tunnel five karst caves , contrast of the water inflow inside the tunnel and the rainfall at the ground surface and tests on the quality of the water.
This article summarize the type and dynamic feature of karst water burst in Yuanliangshan tunnel, by means of analysis of water burst and filling materials of yuanliangshan tunnel five karst caves , contrast of the water inflow inside the tunnel and the rainfall at the ground surface and tests on the quality of the water.
Abstract：
Static loading tests on pile groups with prototype size were carried out in order to study the behaviour of the cap-pile groups-soil in the pile foundation. The soil resistance under the cap, the shaft resistance and the tip resistance of pile were measured by installing various measuring gauges. Based on these test results, clamping action was shown to play an important role. Cap is possessed of weakening effect to pile shaft resistance and strengthening effect to pile tip resistance. Clamping is a complex action. The pile groups efficiency is larger than 1 in the condition of the test. The coaction of pile-soil-cap should be considered in optimum design of pile foundation.
Static loading tests on pile groups with prototype size were carried out in order to study the behaviour of the cap-pile groups-soil in the pile foundation. The soil resistance under the cap, the shaft resistance and the tip resistance of pile were measured by installing various measuring gauges. Based on these test results, clamping action was shown to play an important role. Cap is possessed of weakening effect to pile shaft resistance and strengthening effect to pile tip resistance. Clamping is a complex action. The pile groups efficiency is larger than 1 in the condition of the test. The coaction of pile-soil-cap should be considered in optimum design of pile foundation.
Abstract：
It is common to use the load-transfer curves (p—y curves) or Poulos’s elastic theory to calculate laterally loaded piles at present. This paper discusses the characteristics of these two methods and develops a new coupling analytical solution based on these methods. In the new method, the soil moduli along pile length are calculated by the p—y curves according the stress level and lateral displacements of soil, then the elastic theory is used to account for the soil-pile interaction between different elements using the above soil modulus. The results of the proposed coupling method is reasonable as shown by comparing lateral behavior of the pile with the above two methods.
It is common to use the load-transfer curves (p—y curves) or Poulos’s elastic theory to calculate laterally loaded piles at present. This paper discusses the characteristics of these two methods and develops a new coupling analytical solution based on these methods. In the new method, the soil moduli along pile length are calculated by the p—y curves according the stress level and lateral displacements of soil, then the elastic theory is used to account for the soil-pile interaction between different elements using the above soil modulus. The results of the proposed coupling method is reasonable as shown by comparing lateral behavior of the pile with the above two methods.
Abstract：
In the present paper, the physical experiments and numerical simulations on the failure of concrete model were carried out to investigate the effect of SCA (soundless cracking agent). The test results show that the failure pattern of the concrete model with a single hole is not similar to the excavating marble, where a second crack initiated on the symmetric point after a crack formed in the model as commonly considered, but three main cracks formed in the model. In addition, the numerical results reproduced the whole process of the crack initiation, propagation, and coalescence.
In the present paper, the physical experiments and numerical simulations on the failure of concrete model were carried out to investigate the effect of SCA (soundless cracking agent). The test results show that the failure pattern of the concrete model with a single hole is not similar to the excavating marble, where a second crack initiated on the symmetric point after a crack formed in the model as commonly considered, but three main cracks formed in the model. In addition, the numerical results reproduced the whole process of the crack initiation, propagation, and coalescence.
Abstract：
According to the practice of grouting engineering of BaoDian mineshaft lining fracture treatment, the construction technology of bottom-up perforation grouting suitable for ultradeep (not less than 100 meters) soil ground grouting is described in detail, the most commonly-encountered engineering accident is pointed out and the accident prevention method is proposed. The grouting pressure is studied by field measurement; then“the hydraulic fracturing theory”and “the energy analysis principle for fracturing” are used to analyze gymnostomous grouting and the flux control method is applied for fracturing grouting and range. At last, diffusing way of the single bore grouting are deduced by drilling-core and some engineering phenomenon. The data and conclusion presented in this paper are valuable as a reference for design and construction of similar grouting projects.
According to the practice of grouting engineering of BaoDian mineshaft lining fracture treatment, the construction technology of bottom-up perforation grouting suitable for ultradeep (not less than 100 meters) soil ground grouting is described in detail, the most commonly-encountered engineering accident is pointed out and the accident prevention method is proposed. The grouting pressure is studied by field measurement; then“the hydraulic fracturing theory”and “the energy analysis principle for fracturing” are used to analyze gymnostomous grouting and the flux control method is applied for fracturing grouting and range. At last, diffusing way of the single bore grouting are deduced by drilling-core and some engineering phenomenon. The data and conclusion presented in this paper are valuable as a reference for design and construction of similar grouting projects.
Abstract：
Aimed at several disadvantages such as partial search, the fixedness of the value of reflection factor and the ignorance of the complex diversity in the approach of the basic complex method, the corresponding improvements upon the above disadvantages defined as dynamic full reflection and retraction operator and the rule of most redundant design point to be reflected are presented. Not only the information of the design space but also the objective function value is utilized to determine the redundant design point. The basic complex method and the new kind of complex method are respectively employed to locate the critical failure surface with true minimum factor of safety of non-homogeneous soil slope , and the comparison of the results has shown that the percent of successful run of the new complex method is higher than that of the basic complex method.
Aimed at several disadvantages such as partial search, the fixedness of the value of reflection factor and the ignorance of the complex diversity in the approach of the basic complex method, the corresponding improvements upon the above disadvantages defined as dynamic full reflection and retraction operator and the rule of most redundant design point to be reflected are presented. Not only the information of the design space but also the objective function value is utilized to determine the redundant design point. The basic complex method and the new kind of complex method are respectively employed to locate the critical failure surface with true minimum factor of safety of non-homogeneous soil slope , and the comparison of the results has shown that the percent of successful run of the new complex method is higher than that of the basic complex method.
Abstract：
For the applications of coaxial-cable electromagnetic wave reflection technique to slope monitoring, principles of the technique and the properties of electromagnetic wave propagation in coaxial cable were described herein. Based on the results of laboratory tests, the in-situ slope monitoring method with the technique was proposed. From the in-situ monitoring results, it was found out that the location of the sliding surface can be determined accurately. Comparatively, the sensitivity of coaxial cable with small diameter was higher than that of cable with large diameter.
For the applications of coaxial-cable electromagnetic wave reflection technique to slope monitoring, principles of the technique and the properties of electromagnetic wave propagation in coaxial cable were described herein. Based on the results of laboratory tests, the in-situ slope monitoring method with the technique was proposed. From the in-situ monitoring results, it was found out that the location of the sliding surface can be determined accurately. Comparatively, the sensitivity of coaxial cable with small diameter was higher than that of cable with large diameter.
Abstract：
Based on imaginary piles model, integral equation approach was applied to analyze composite foundation with hybrid piles. By simulating the cushion with the Winkler spring, the effect of cushion was taken into consideration, and then the second kind of Fedholm’s equations were deduced to solve the problems. Using the numerical calculation, compression of cushion, loads shared by piles and subsoil, load transfer characters and stress distribution of subsoil were obtained. Comparison with the finite element method and experiment results verified the accuracy of the present calculation method. Finally, the influences of pile length on the working behavior of the foundation were studied. The present method is suitable to analysis the foundation under working loads.
Based on imaginary piles model, integral equation approach was applied to analyze composite foundation with hybrid piles. By simulating the cushion with the Winkler spring, the effect of cushion was taken into consideration, and then the second kind of Fedholm’s equations were deduced to solve the problems. Using the numerical calculation, compression of cushion, loads shared by piles and subsoil, load transfer characters and stress distribution of subsoil were obtained. Comparison with the finite element method and experiment results verified the accuracy of the present calculation method. Finally, the influences of pile length on the working behavior of the foundation were studied. The present method is suitable to analysis the foundation under working loads.
Abstract：
Based on coupling of long-term prestress loss of anchor tie and slope creep, a new mode is built and the theoretical function of long-term prestress variation is put forward. By comparison with the experiment result and FEM result , the suggested model is proved to be applicable.
Based on coupling of long-term prestress loss of anchor tie and slope creep, a new mode is built and the theoretical function of long-term prestress variation is put forward. By comparison with the experiment result and FEM result , the suggested model is proved to be applicable.
2005, 27(4): 468-473.
Abstract：
In this article, the caustics method and holo-photoelasticity method are used to investigate the distribution of contact forces inside a pack of discrete square cells submitted to a compressive load. Our results demonstrate that the collective response of the pack contradicts the traditional elasticity theory predictions and supports a description by equations of the parabolic type. These results are significant to solve problems in soil mechanics.
In this article, the caustics method and holo-photoelasticity method are used to investigate the distribution of contact forces inside a pack of discrete square cells submitted to a compressive load. Our results demonstrate that the collective response of the pack contradicts the traditional elasticity theory predictions and supports a description by equations of the parabolic type. These results are significant to solve problems in soil mechanics.
2005, 27(4): 474-477.
2005, 27(4): 478-481.
